1. The Field of the Invention
This invention relates generally to the field of trailer dumping systems. More particularly this invention relates to an apparatus that tips or rotates trailers to unload their contents.
2. The Background Art
Trucks frequently carry cargo comprising comparatively small loose particles such as coal, gravel, or hog fuel (large sections of tree bark burned for heating purposes). Various mechanisms exist to unload such cargo. For example the underside of a vehicle may have a trapdoor that is opened to release the cargo. Such a system requires either that a receiving structure be positioned directly beneath the trapdoor or that the cargo be released while the vehicle is in motion to avoid dragging the wheel assembly through large mounds of material.
Such systems have significant disadvantages for cargo that is not comparatively dense. For such cargos, a unitary or trailing vehicle's volume must be maximized in order to approach the weight bearing capacity of the frame and engine or of a towing vehicle. Providing a trapdoor and an actuator to open and close a trapdoor on the underside of a vehicle takes clear, unsupported space and necessitates larger structural members to compensate for the weakness created by the opening. Furthermore, the size of a trapdoor must necessarily be limited to avoid structural weakness. Therefore, bulky and irregular cargos will be likely to jam when unloading.
Other systems provide an opening on top of a vehicle and unload cargo by rotating the entire vehicle such that the cargo falls out the top. However, such systems require a great deal of time and energy to lift and rotate the vehicle through an angle of 140 degrees or more.
Still other systems provide doors at the rear of a vehicle and unload the vehicle by raising the front of the vehicle relative to the rear so that the cargo flows out the rear doors. Such systems have the disadvantage of requiring a great deal of space, energy, and power to lift the center of gravity of the vehicle to a sufficient height for the contents of the vehicle to flow out. Furthermore, the size of the opening at the rear of the vehicle is typically limited to the width of the vehicle. Where the cargo is bulky and irregularly shaped, such an opening may cause the cargo to bridge or otherwise jam during unloading.
Thus it would be an advancement in the art to provide a system that allows for unloading of bulky, irregularly shaped cargos, such as debris, long objects, and so forth. Such a system would provide a large, clear, unobstructed opening that would not require excessive lifting or tilting of the vehicle to unload the cargo. It would be a further advancement in the art to provide a large opening of substantially the dimension of the cargo hold, facilitating unloading while preserving the structural integrity of the vehicle.